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ABSTRACT Objective: The objective of this study was to determine how arch form and interproximal contact size displace mandibular teeth subjected to an anterior component of force (ACF). Methods: Nine finite element models (FEM) of the mandibular arch were developed using Ansys® v. 16.0 software. They were designed to evaluate the effects of three arch forms (triangular, oval, and square) and three contact sizes (point-to-point, 1 mm diameter, and 2 mm diameter). All nine models were subjected to an ACF of 53.8 N (5486 gm). Three-dimensional tooth rotations and displacements of the mandibular teeth were evaluated, from the right first molar to the left first molar. Results: Arch form had a greater effect on tooth movements than contact size. Triangular arches and point-to-point contacts produced the greatest displacements and rotations of teeth. Oval arches with 2 mm wide interproximal contact points showed the greatest stability. The right first premolar showed the greatest displacements in all of the models. Conclusions: Arch form and contact size affect interproximal tooth stability. Teeth are least stable in narrow arches with point-to-point interproximal contacts, and most stable in wider arches with larger contacts.
RESUMO Objetivo: O objetivo deste estudo foi determinar como o formato da arcada e o tamanho do contato interproximal deslocam os dentes inferiores submetidos a um componente anterior de força (CAF). Métodos: Nove modelos de elementos finitos (MEF) da arcada inferior foram desenvolvidos utilizando o software Ansys® v. 16.0. Eles foram projetados para avaliar os efeitos de três formatos de arcada (triangular, oval e quadrado) e três tamanhos de contato interproximal (ponto a ponto, 1 mm de diâmetro e 2 mm de diâmetro). Todos os nove modelos foram submetidos a um CAF de 53,8 N (5486 gm). Foram avaliados tridimensionalmente as rotações dentárias e os deslocamentos dos dentes inferiores, do primeiro molar direito ao primeiro molar esquerdo. Resultados: A forma da arcada teve um efeito maior no movimento dos dentes do que o tamanho do contato interproximal. Arcadas triangulares e contatos ponto a ponto produziram os maiores deslocamentos e rotações dos dentes. Arcadas ovais com pontos de contato interproximal de 2 mm de largura apresentaram maior estabilidade. O primeiro pré-molar direito apresentou os maiores deslocamentos em todos os modelos. Conclusões: O formato da arcada e o tamanho do contato interproximal afetam a estabilidade dos dentes. Os dentes foram menos estáveis nas arcadas estreitas com contatos interproximais ponto a ponto, e mais estáveis nas arcadas mais largas com contatos maiores.
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Background: A new classification called OXIS was proposed for categorising the interproximal contacts of primary molars, and its prevalence was established. The aim of this study was to establish the variations in interproximal contacts of primary canines and thereby modify the OXIS classification of primary molars to primary canines. Additionally, we aimed to estimate the applicability of modifications to primary anterior teeth. Methods: A retrospective study was conducted with sectional die models obtained from a previous study of 1,090 caries-free children. Two calibrated examiners evaluated a total of 4,674 contacts from the occlusal aspect. The contacts were scored according to the former OXIS classification, with two modifications incorporated to encompass the morphological differences and rotations of primary canines and other primary anterior teeth. Results: The most prevalent contact was O (62.1%), followed by X (19.6%), I (12.6%), S type I (4.1%), and S type II (1.6%). Inter-arch comparison by means of the Chi-square test revealed significant differences for all types of contacts ( P < .001). Conclusions: The interproximal contacts of canines were categorised as O, X, I, S I, and S II. The OXIS classification of primary molars was modified to befit the variations in primary canines. This study showed the presence of different types of contacts in primary canines. Identification of these contacts and their complexity has warranted a need for this to be studied as an inherent risk factor for caries risk assessment.
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The interdental papilla plays an important role in terms of esthetics and function. Management of the interdental papilla, especially around implants can be challenging. One of the factors mentioned in the literature that affects the viability of the papilla is the distance of the interdental contact point from the crest of the bone. The following case report describes a technique to predictably achieve an interdental contact area within the proper distance from the crest of the bone to help maintain the papilla for the long term.